Method and device to improve print quality of gray scales and color for printers

Abstract

Method to improve the printing quality at reproduction of half-tone originals by means of printers of the type, in which a number of dots are brought together in a cell (pixel). A minimum of two dots form a cell where each dot in the cell is controlled individually with respect to the size and/or the color value. The dots form a pattern in each cell, which is variable with respect to the number of dots, the dot size and/or the dot color value.

What is claimed is: 
     
       1. Method of halftone printing in which an information carrier is brought into electrical cooperation with an electrode matrix, the information carrier being movable relative to the electrode matrix, and the electrode matrix including electrodes connectable to at least one voltage source for applying a voltage level to the electrodes for a duration of time, the electrodes forming a number of cells for creating images, each cell including a plurality of dots, which method comprises: individually controlling the size, shape and/or amount of color of each dot such that the dots form a preselected pattern in which at least some of the dots vary in amount of color from other of the dots, the size of the dots and the amount of color being controlled by changing the speed of movement of the information carrier relative to the electrode matrix, the voltage level applied to and/or the application time of the voltage applied to the electrodes of the electrode matrix.   
     
     
       2. Method according to claim 1, in which the voltage source is derived from control means including a control circuit for receiving image data and in which the method further includes: (a) defining a time slot;   (b) monitoring the time slot to determine if any image data is available to be sent to the control circuit;   (c) sending the image data to the control circuit; and   (d) repeating steps (b) and (c) until no image data is available.   
     
     
       3. Method according to claim 2, in which the control means includes a latch and the image data is sent through the latch circuit to the control circuit. 
     
     
       4. Method according to claim 2, in which the control means includes a latch and a counter and the image data is sent through the latch and the counter to the control circuit. 
     
     
       5. Apparatus for halftone printing in which an information carrier is brought into electrical cooperation with an electrode matrix, the information carrier and the electrode matrix being movable relative to each other, and the electrode matrix including electrodes connectable to at least one voltage source, the electrodes forming a number of cells for creating images, each cell including a plurality of dots, which apparatus comprises: means for individually controlling the size, shape and/or amount of color of each dot in accordance with received image data such that the dots form a preselected pattern in which at least some of the dots vary in amount of color from other of the dots, the individually controlling means including means for changing the speed of movement of the information carrier and the electrode matrix relative to each other, the voltage level applied and/or the application time of the voltage applied to the electrodes of the electrode matrix.   
     
     
       6. Apparatus according to claim 5, wherein the electrode matrix comprises apertures at least partly surrounded by the electrodes. 
     
     
       7. Apparatus according to claim 5, wherein the electrode matrix comprises a plurality of conductors arranged on an insulating member having pervious holes and the holes are surrounded by said conductors. 
     
     
       8. Apparatus according to claim 5, in which the control means comprises first and second circuits and the image data is serially sent to the first circuit and is outputted from the first circuit in parallel form to the second circuit, the second circuit being time controlled to provide data to the electrode means with a predetermined frequency. 
     
     
       9. Apparatus according to claim 8, in which the first and second circuits form an integrated unit. 
     
     
       10. Apparatus according to claim 5, in which the control means includes a time controlled circuit for receiving and outputting the data with a predetermined frequency. 
     
     
       11. Apparatus according to claim 5, wherein the electrode matrix includes a net of electrodes, surrounding a plurality of apertures, each electrode being connected to the at least one voltage source, the output of which is controllable in respect of the voltage output, time and/or the voltage level. 
     
     
       12. Method for improving the quality of printing and increasing printing speed in a printing device when producing halftone images on an information carrier, wherein said device includes control means and at least one printer means having at least one print element which controls transportation of a coloring agent from a carrier towards the information carrier and being arranged to produce dots, which method comprises: generating with said printer means a number of cells for creating images, each cell comprising at least one dot; and   controlling simultaneously the color value and size of each individual dot in each cell by controlling said print element by control signals from said control means to form a pattern which is variable with respect to the number of dots and the colour value and size of the dots.   
     
     
       13. Device for improving the quality of printing and increasing printing speed in a printing device when producing halftone images on an information carrier, which device comprises: at least one printer means comprising at least one print element, said print element being arranged to control transportation of a coloring agent from a carrier towards said information carrier to produce dots, and said printer means being arranged to generate a number of cells for creating images, each cell comprising at least one dot;   control means for generating control signals to control said printer element to produce said dots; and   said print means being further arranged to simultaneously control, in response to control signals from said control means, the color value and size of each individual dot in each cell to enable forming of a pattern which varies with respect to the number of dots and the color value and size of the dots.   
     
     
       14. Method to improve quality of printing when producing halftone images on an information carrier using at least one printer, in which a number of cells are used for creating images, each cell including a number of dots, the method comprising: varying the number of dots in at least some of the cells; and   controlling the color value and size of each dot in the cells, so that the dots in each cell form a preselected pattern wherein the pattern in some of the cells varies from the pattern in other of the cells with respect to the number of dots, the color value and the size of the dots.